Sep 10, 2010 13:00 GMT  ·  By

A key milestone in the development process of Firefox 4.0 was postponed, Mozilla confirmed officially. This is not the first time that the Firefox 4.0 project has suffered delays, but the fact of the matter is that they never were all that consistent, usually just a few days at most.

With Beta 5 delivered, Mozilla is now hard at work on Beta 6, but also on wrapping up the feature set for the next iteration of its open source browser.

Initially, September 10th, 2010 was supposed to be synonymous with the feature freeze milestone for Firefox 3.6’s successor.

This will not be the case revealed Mike Beltzner, Mozilla’s Director of Firefox. “To ensure that there is a long enough amount of "bake time" for blockers, I have decided that we will be delaying the upcoming code freeze for Firefox 4 Beta 6, originally scheduled to be tomorrow,” he stated on September 9th.

According to data provided by the browser vendor, on September 6th, there still were some 114 blockers that needed to be resolved before Firefox 4.0 Beta 6 could be delivered to testers.

Mozilla refers to bugs severe enough to impact the delivery of a new development milestone as blockers.

In total, over 700 blockers still need to be resolved ahead of the release of Firefox 4.0 Beta 6, with at least two more Beta Builds already planned after the Beta 5 release.

In order to make the late 2010 launch deadline set for the next version of Firefox, Mozilla has started dropping features from the browsers, with Account Manager the first to go, followed by Inspector.

Additional features are at risk of being cut off, but Mozilla still has to make a final decision.

One thing is clear however, the feature set that will be delivered with Firefox 4.0 Beta 6 will be final, meaning that Mozilla will not introduce any new features after the upcoming testing milestone of the open source browser.

However, early adopters should not expect the Firefox 4.0 Beta 6 and feature freeze milestone to be more than a few days.

Overall, Mozilla has been extremely focused on making sure that it will be able to finalize and ship Firefox 4.0 by the end of 2010, even if a tad later than October / November as initially intended.

Firefox 4.0 Beta 5 for Windows is available for download here.

Firefox 4.0 Beta 5 for Mac OS X is available for download
here.

Firefox 4.0 Beta 5 for Linux is available for download
here.